Creamy Mustard Dipping Sauce with Chicken Sausage

1 (17.3-oz.) pkg. frozen puff pastry sheets, thawed 1 (12-oz.) pkg. fully cooked chicken sausage, links, sliced about ¼” thick 1 large egg, lightly beaten 3 T. Dijon or Creole mustard ½ c. sour cream 1. Preheat oven 400. 2…